Change ADCXYPRES_A fallback

Author: Sh3Rm4n

src/adc.rs

@@ -528,7 +528,6 @@ macro_rules! adc {
                         Some(pllclk) if !cfgr2.read().$adcXYpres().is_no_clock() => {
                             pllclk
                                 / match cfgr2.read().$adcXYpres().variant() {
-                                    Variant::Val($ADCXYPRES_A::DIV1) => 1,
                                     Variant::Val($ADCXYPRES_A::DIV2) => 2,
                                     Variant::Val($ADCXYPRES_A::DIV4) => 4,
                                     Variant::Val($ADCXYPRES_A::DIV6) => 6,
@@ -539,8 +538,8 @@ macro_rules! adc {
                                     Variant::Val($ADCXYPRES_A::DIV32) => 32,
                                     Variant::Val($ADCXYPRES_A::DIV64) => 64,
                                     Variant::Val($ADCXYPRES_A::DIV128) => 128,
-                                    // TODO: I think that it not correct
-                                    _ => 256,
+                                    Variant::Val($ADCXYPRES_A::DIV256) => 256,
+                                    _ => 1,
                                 }
                         }
                         _ => {